Automobiles include multiple electrical subsystems (or “auxiliary loads”) that utilize electrical energy when the vehicle is running, and may also utilize electrical energy provided by the vehicle's battery when the engine is in an inactive or power-off condition. In order to preserve sufficient power for all electrical subsystems, measures must generally be taken to avoid discharging the battery below a predetermined threshold voltage. The construction of the vehicle battery is well-known, and generally comprises a plurality of connected rechargeable lead-acid secondary cells.
In addition to various auxiliary loads powered by the vehicles electrical system, other integrated systems may have generally independent power sources. Managing distribution of vehicle power between multiple power sources remains a challenge.